This invention relates generally to devices for extracting water and other liquids from liquid impregnated materials, such as waste, pulp, raw sewerage and waste water in general, and more particularly, to such a unit in the form of a helical screw undergoing relative rotation with respect to a surrounding drainage screen.
The device which is the subject of this invention finds particular use with a waste disposal apparatus or system wherein upon treatment of the waste material, means must be provided for separating the solids and the liquids from within a slurry. This waste disposal system in general, may or may not include a pulper having a tank containing the waste material, fibrous material, garbage and other disposable waste in the presence of a high percentage of water, all being subjected to the disintegrating action of a rotatable impeller having suitable material disintegrating cutters. (See commonly assigned U.S. Pat. Nos. 2,729,146; 3,164,329; 3,584,800; 3,620,460 and 3,885,745.) In apparatus of this type there is associated with the tank discharge, a means for delivering the water-laden material to a liquid extracting device often referred to as a hydro-extractor in which a helical screw is made to undergo rotation within a cylindrical sieve. The hydro-extractor separates the solids from the liquids by withdrawing the liquid from the material received from the pulper or selected disintegrating or mascerating unit. In U.S. Pat. No. 3,394,649, having a common assignee with this application, there is disclosed such a hydro-extractor in which there is a cylindrical screen or hollow cylindrical sieve surrounding the major portion of the screw.